Systems and methods for ms-bs-ms and ms-rs-ms operation

ABSTRACT

Methods and systems for providing efficient communications between two mobile stations served by the same base station or relay station are provided. A base station maintains information identifying which mobile stations it is serving. When a connection is set up between two mobile stations, if they are both being served by the same base station, the base station forwards traffic directly between the two mobile stations without forwarding it on to higher level network entities.

RELATED APPLICATION

This application claims the benefit of U.S. provisional application No.60/827,334 filed Sep. 28, 2006 hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The invention relates to communications taking a path from a mobilestation to a base station and back to a mobile station, or taking a pathfrom a mobile station to a relay station and back to a mobile station.

BACKGROUND

If two mobile stations MS1 and MS2 are associated with the same basestation (BS) (possibly via one or more relay stations (RS)) and MS1wants to send data to MS2, the operation of the connections set up anddata forwarding by the BS is defined herein as MS-BS-MS operation. Theconventional approach to handling this is through a BSC (base stationcontroller) or gateway server without regard to the fact that MS1 andMS2 are associated with the same BS.

SUMMARY OF THE INVENTION

According to one broad aspect, the invention provides a method offacilitating intra-cell Peer-to-Peer Communication comprising:maintaining a CID mapping identifying each communication between twomobile stations served by a common network transceiver; upon receipt bythe network transceiver of an uplink communication containing an uplinkSDU, determining if there is a corresponding entry in the CID mappingtable and if so, sending a downlink communication containing acorresponding downlink SDU.

In some embodiments, maintaining, determining and sending are performedin a network transceiver that is a base station.

In some embodiments, maintaining, determining and sending are performedin a network transceiver that is a relay station.

In some embodiments, the CID mapping comprises a CID mapping table, andeach entry in the CID mapping table includes a source MS ID and adestination MS ID.

In some embodiments, each entry in the CID mapping table includessecurity information for the UL from the source MS, and securityinformation for the DL to the destination MS.

In some embodiments, the method further comprises: upon receiving theuplink SDU, decrypting the SDU using the security information for theUL, and then re-encrypting using the security information for the DL toproduce the corresponding downlink SDU.

In some embodiments, the method further comprises: maintaining aconnection information table for the BS that includes all connectionsthat are served by this BS; upon receipt of a packet from a source thatis included in the connection information table for a destination thatis included in the connection information table, adding an entry intothe CID mapping.

In some embodiments, the method further comprises: upon receipt of firstSDU for a destination that is being serviced by the same base station,establishing a downlink service flow to the destination.

In some embodiments, the downlink service flow is established using anexisting security association.

In some embodiments, the downlink service flow is established using adynamic security association.

According to another broad aspect, the invention provides a base stationcomprising: at least one antenna for receiving uplink communications andtransmitting downlink communications; an uplink packet processor thatprocesses uplink packets by: a) maintaining a CID mapping identifyingeach communication between two mobile stations served a common networktransceiver; b) upon receipt by the network transceiver of an uplinkcommunication containing an uplink SDU, determining if there is acorresponding entry in the CID mapping table; and a downlink packetprocessor that, upon there being a determination that there is acorresponding entry in the CID mapping table for an uplink SDU, sends adownlink communication containing a corresponding downlink SDU.

According to another broad aspect, the invention provides a relaystation comprising: at least one antenna for receiving uplinkcommunications and transmitting downlink communications; an uplinkpacket processor that processes uplink packets by: a) maintaining a CIDmapping identifying each communication between two mobile stationsserved a common network transceiver; b) upon receipt by the networktransceiver of an uplink communication containing an uplink SDU,determines if there is a corresponding entry in the CID mapping table;c) a downlink packet processor that, upon there being a determinationthat there is a corresponding entry in the CID mapping table for anuplink SDU, sends a downlink communication containing a correspondingdownlink SDU.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theattached drawings in which:

FIG. 1 is a flowchart of an example method of table creation and updateMS-BS-MS Operation Flow Chart of BS-1 for a case where source anddestination addresses are in CS TLV compound of RSA-XXX message;

FIG. 2 is a flowchart of an example method of table creation and updateMS-BS-MS Operation Flow Chart of BS-1 for a case where source anddestination addresses are not in CS TLV compound of RSA-XXX message;

FIG. 3 is a flowchart of MS-BS-MS operation for Data forwarding; and

FIG. 4 is a block diagram of SDU processing.

DETAILED DESCRIPTION OF EMBODIMENTS

The conventional approach to handling MS-BS-MS operation through a BSC(base station controller) or gateway server without regard to the factthat MS1 and MS2 are associated with the same BS causes unnecessarydelay and resource wastage.

Embodiments of the invention provide systems and methods that providemore efficient traffic handling for the case where two MSs that arecommunicating are connected to the same base station or relay station.

An MS connection information Table is maintained that includesparameters for the connections of each mobile station served by the BS.In a particular example, the fields are SFID (service flow ID), UL CID(uplink connection ID), DL CID (downlink connection ID), SAID (securityassociation ID), possibly including a (TEK) (traffic encryption key) andQoS (quality of service). The form that each of the parameters referredto might take is implementation specific. More generally, theinformation maintained in respect of each MS connection can be definedon an implementation specific basis. An example of a MS connectioninformation table is provided below in Table 1. TABLE 1 MS connectioninformation table MS1 (IP SFID UL CID SAID (TEK) QoS address or SFID ULCID SAID (TEK) QoS other . . . . . . . . . . . . equivalent SFID DL CIDSAID (TEK) QoS address) SFID DL CID SAID (TEK) QoS MS2 (IP SFID UL CIDSAID (TEK) QoS address or SFID UL CID SAID (TEK) QoS other . . . . . . .. . . . . equivalent SFID DL CID SAID (TEK) QoS address) SFID DL CIDSAID (TEK) QoS . . . . . . . . . . . . . . .

An entry can be added to this table each time an UL or DL service flowis set up. In some embodiments, the SFID, SAID, CID and QoS are assignedby the network, for example by a base station and/or another networkcomponent.

MAC (medium access control) features are often organized into layers.One set of layers includes a convergence sub-layer (CS), common partsub-layer (CPS), and security sub-layer, although the security sub-layeris sometimes referred to as a component rather than a sub-layer. Moregenerally, layer definitions are implementation specific.

In a specific example, the source address of a MS may be indicated in aCS source address TLV (type, length, value) in a DSA-REQ (dynamicservice add request) or may be indicated in a CS destination address TLVof DL DSA-RSP (dynamic service add response).

A CID (connection identifier) mapping table is maintained that hasentries that each represent a respective established communicationbetween two MSs served by the BS. Table 2 below provides a specificexample of the form such a table might take. MS ID UL SAID MS ID DL SAID(or basic ID) CID (TEK) (or basic ID) CID (TEK) . . . . . . . . . . . .. . .In the example illustrated, the first column contains the MS ID for thesource, and the fourth column contains an MS ID entry (fourth column)for the destination. In some embodiments, the MS ID is a MAC ID, forexample a 48 bit MAC ID. In other embodiments, the MS ID is a shorterbasic ID (for example 16 bits) that is unique within the network. Thisis more efficient to use than the full MAC ID. Each entry in the CIDmapping table indicates a UL CID and corresponding DL CID, as well asthe SA parameters (SAID) for each of these connections. The UL CID is aCID for uplink traffic from a source MS to the base station for a givenestablished communication between two MSs served by the BS. The DL CIDis a CID for downlink traffic from the base station to the destinationMS for the given established communication between two MSs served by theBS. In the event there is to be bi-directional communications, therewould be two entries in the table, one for each direction, with thesource and destination roles reversed.

The following are two examples of triggers for DL service flow set upthat result in the creation of an entry in the CID mapping table.

First Example

After an UL connection is setup from a MS served by a BS, if thedestination address of the UL connection matches a MS's source addressin the MS connection information table, then a DL service flow to theidentified MS is established, and an entry is added to the CID mappingtable.

Second Example

If the destination address in the very first SDU (Service data unit) ona UL connection matches a MS's source address in the MS connection infoTable, then a DL service flow to the identified MS is established, andan entry is added to the CID mapping table.

In some embodiments, in order to establish the DL service flow, the BSmay initiate a dynamic SA creation procedure per 7.3 (802.16d). The BSinitiates DL service flow establishment procedure by sending DSx-XXXmessage, including the SAID, SFID, DL CID, QoS parameter set, etc. Theuse of dynamically assigned SA may solve a potential problem of multipletransmitters transmitting to the same receiver. In some embodiments, thePN synchronization between RS and BS is performed to avoid thispotential problem.

In some embodiments, the new DL service flow is established using anexisting SA. Multiple services can be mapped to a single SA (securityassociation).

After the CID mapping table is established, L2 routing, instead of L3routing, can be implemented to forward traffic. More specifically, theConnection ID (CID) is used to identify the destination connection,instead of using IP mapping.

Note that while the BS is described as creating the CID mapping table,more generally, any appropriate network entity may do this. Otherexamples include a BSC or a gateway. If an entity other than BS, createsthe CID mapping table, that entity forwards the table to the BS for usein processing traffic.

For each received MAC PDU (payload data unit) on an UL connection thatcontains a CID listed in the CID mapping table the base station performsthe following procedure:

-   -   Decrypt the payload (privacy enabled service flow) using the        corresponding UL connection TEK;    -   Restore SDU;    -   Create DL MAC PDU and encrypt using corresponding the DL        connection TEK (for a privacy enabled connection); and    -   Send the MAC PDU on the corresponding DL connection.        Extension of MS-BS-MS to MS-RS-MS

In some embodiments, if the source MS and destination MS of a data floware both attached to a common RS (possibly via other RSs) the MS-BS-MSoperation described above is applied to MS-RS-MS operation.

To achieve this, whenever a new entry in a CID mapping table is created(for example by a BS), the network (for example the BS) checks todetermine whether both involved MSs are attached to a common RS(possibly via other RSs). If such an RS exists, BS forwards relevantinformation from the CID mapping table, for example a sub-tablecontaining only the relevant entry, and corresponding SA materials tothe RS.

At that point, the RS starts the same data forwarding operation asdescribed above for the BS.

If a dynamic SA is established for the DL CID, there is no need forpossible PN sequence number (used to identify the replay)synchronization between BS and RS. In some embodiments, the PN sequencenumber used by BS for other SF is identified to the RS and vice versa.

FIG. 1 is a flowchart of an example method of table creation and updateMS-BS-MS Operation Flow Chart of BS-1 for a case where source anddestination addresses are in CS TLV compound of RSA-XXX message.

FIG. 2 is a flowchart of an example method of table creation and updateMS-BS-MS Operation Flow Chart of BS-1 for a case where source anddestination addresses are not in CS TLV compound of RSA-XXX message.

FIG. 3 is a flowchart of MS-BS-MS operation for Data forwarding.

MS-BS-MS Operation in Stand-Alone Mode

In some embodiments, a stand-alone mode of operation is provided thatcan be used in a BS when the BS has no connection with the network (e.g.no connection with other BS and any other control entities residing innetwork side).

In some embodiments, when this is to occur, the BS announces “enterstand-along mode” using a signalling message, which means communicationcan only happen among MSs/RSs associated with this BS.

MSs that have passed authorization before entering “stand alone mode”,are authorized to continue MS-BS-MS communication until reauthorization.At reauthorization, MS and BS may for example use RSA based procedureper 802.16e 7.8.2. Reauthorization might take place again for exampleafter an AK (authorization timer) expires. Reauthorization may bepossible without network involvement other than the BS.

A second option is again allow it to continue, but then to disablereauthorization. In some implementations, the MSs can no longercommunicate. In other cases they are allowed to continue communicating.

The procedures that are followed have been described above, the onlydifference being that now MSs communicate with the BS while the BS isnot in communication with the network. As such, only limitedcommunication is possible.

MS-RS-MS Operation in Stand-Alone Mode

In some instances, a RS may lose its connection with the BS (noconnection with network side) due to some unpredictable reasons. In someembodiments, a mode of operation in the RS is provided that is the sameas that of MS-BS-MS operation in stand alone mode.

In some embodiments, for this implementation, the RS is configured toimplement a full set of MAC common part sub-layer (CPS) and mayimplement part of a convergence sub-layer (CS).

Referring to FIG. 4, shown is a block diagram of a BS with convergencesub-layer function to enable MS-BS-MS Operation. Note that if headersuppression is not implemented, the SDU and corresponding CID transfercan be moved to MAC common part sub-layer (CPS).

A route function is provided that functions as follows:

upon receiving a SDU (service data unit) from the UL, the destinationaddress is filtered. If the destination address is within the table, theSDU is routed to a DL convergence sub-layer; otherwise routed to upperlayer through SAP (service access point).

Referring again to FIG. 4, in the left hand portion of the figure:

a packet is received from an MS or associated RS; this is reconstructed,and then subject to destination address filtering with the table thatincludes all addresses covered by the BS. If the address is not present,the packet is passed on to the SAP (service access point), and then onto an upper layer entity. If the address is present, the packet ispassed over to the DL convergence sub-layer, this being thefunctionality shown in the right hand side of the figure.

In the right hand side of the drawing:

a packet is received that is destined to another address that is servedby that BS. DL classification and CID mapping is performed, and thepacket goes out to another MS or associated RS.

In another embodiment, a similar design to that of FIG. 4 is employed ina RS.

The description of MS-BS-MS and MS-RS-MS are appropriate examples forwhere 802.16e is used to support this operation. Any other cellularsystem with or without relay stations can use a similar approach.

The CID mapping table described is an appropriate example table where802.16e is used to support MS-BS-MS and MS-RS-MS. Any other type oftables which include any other MS identity could be possible for routingpackets of MS or other relay stations by BS or relay station.

What has been described is merely illustrative of the application of theprinciples of the invention. Other arrangements and methods can beimplemented by those skilled in the art without departing from thespirit and scope of the present invention.

1. A method of facilitating intra-cell Peer-to-Peer Communicationcomprising: maintaining a CID mapping identifying each communicationbetween two mobile stations served by a common network transceiver; uponreceipt by the network transceiver of an uplink communication containingan uplink SDU, determining if there is a corresponding entry in the CIDmapping table and if so, sending a downlink communication containing acorresponding downlink SDU.
 2. The method of claim 1 whereinmaintaining, determining and sending are performed in a networktransceiver that is a base station.
 3. The method of claim 1 whereinmaintaining, determining and sending are performed in a networktransceiver that is a relay station.
 4. The method of claim 1 whereinthe CID mapping comprises a CID mapping table, and each entry in the CIDmapping table includes a source MS ID and a destination MS ID.
 5. Themethod of claim 2 wherein each entry in the CID mapping table includessecurity information for the UL from the source MS, and securityinformation for the DL to the destination MS.
 6. The method of claim 5further comprising: upon receiving the uplink SDU, decrypting the SDUusing the security information for the UL, and then re-encrypting usingthe security information for the DL to produce the correspondingdownlink SDU.
 7. The method of claim 1 further comprising: maintaining aconnection information table for the BS that includes all connectionsthat are served by this BS; upon receipt of a packet from a source thatis included in the connection information table for a destination thatis included in the connection information table, adding an entry intothe CID mapping.
 8. The method of claim 1 further comprising: uponreceipt of first SDU for a destination that is being serviced by thesame base station, establishing a downlink service flow to thedestination.
 9. The method of claim 8 wherein the downlink service flowis established using an existing security association.
 10. The method ofclaim 8 wherein the downlink service flow is established using a dynamicsecurity association.
 11. A base station comprising: at least oneantenna for receiving uplink communications and transmitting downlinkcommunications; an uplink packet processor that processes uplink packetsby: a) maintaining a CID mapping identifying each communication betweentwo mobile stations served a common network transceiver; b) upon receiptby the network transceiver of an uplink communication containing anuplink SDU, determining if there is a corresponding entry in the CIDmapping table; and a downlink packet processor that, upon there being adetermination that there is a corresponding entry in the CID mappingtable for an uplink SDU, sends a downlink communication containing acorresponding downlink SDU.
 12. A relay station comprising: at least oneantenna for receiving uplink communications and transmitting downlinkcommunications; an uplink packet processor that processes uplink packetsby: a) maintaining a CID mapping identifying each communication betweentwo mobile stations served a common network transceiver; b) upon receiptby the network transceiver of an uplink communication containing anuplink SDU, determines if there is a corresponding entry in the CIDmapping table; c) a downlink packet processor that, upon there being adetermination that there is a corresponding entry in the CID mappingtable for an uplink SDU, sends a downlink communication containing acorresponding downlink SDU.